Arc rectifier



July 6,1926. 1,591,185

I E. H. ROLLINSON ARC RECTIFIER Filed.April 16, 1921" UVVfA/TOR.

A TTORNE Y.

Patented July 6, 1926.

UNITED STATES 1,591,185 PATENT OFFICE.

EARL H. ROLLIN SON, OF LYONS FARMS, NEW JERSEY, ASSIGNOR TO COOPER HEWITT ELECTRIC COMPANY, OF HOBOKEN, NEW JERSEY, A CORPORATION OF NEWJERSEY.

ARC RECTIFIER.

"Application filed April 16, 1921. Serial No. 461,886.

It has been known for a long time that a hot and a cold electrode within a vacuum tube will act as a rectifier, and when such tube is filled with an inert gas the voltage drop between the anode and the cathode is materially reduced, in some cases to as low as 5 volts. For this reason, the rectifier bulb is coming into more extensive use as refinements of manufacture are introduced.

The life of the rectifier bulb as ordinarily used is normally about 800 hours. One of the causes of the breaking down of the cathode, which is usually a closely coiled tungsten filament, is the excessive heating of one end while the other is barely red. Under these conditions, the filament becomes weakened along the excessively heated zone, and begins to sag and will shortly be ruptured, sometimes long before the usual period of warranty has. expired.-

My improvement relates to are rectifiers of the type above referred to, and has more particularly to do with the combination of an arc rectifier bulb with certain adjuncts which serve to lengthen. its life, and also to introduce certain elements of safety which prevent the burning out or rupture of thebulb filament because of current fluctuation. More particularly, my improvement embodies means for uniformly heating the cathode, so as to avoid excessively hot spots or sections in the filament. 1th my improve- I ment the normal life of the bulb is lengthened or more, or up to about 1200 hours, as a minimum quaranteed life.

In the accompanying drawing illustrating my 1nvent1onz-- Fig. l is a wiring plan showing the rela: tive location of the several elements of a rectifying outfit after the current consum ing devices are coupled into the D. C. line.

Fig. 2 is a wiring plan of an outfit designed to take care of the whole A. C. wave by the con'ibination of two half wave rectifier bulbs. i

Fig. 3 is a diagram of the two half wave Fig. 6 is a plan of a detached panel upon which the time limit cut-out, the relay and tripping means are mounted, for installation 'in existing rectifier outfits of the old type.

Fig. 7 is a wiring diagram of a rectifier outfit, showing a hand operated switch located in the cathode leads.

Figs. 8, 9 and 10 illustrate the different positions of the switch to accomplish the resultsdescribed.

The apparatus making up the rectifier outfit comprises the transformer T; the rectifier bulb B, of well-known formand-construction; the relay R; the current consuming devices S, in this case a storage battery to be charged; the alnmeter A; the time limit cut-out C; and thedial switch 19.

The wire 4 is tapped into the transformer secondary at 5, and leads to the filament 6, from which the wire 7 leads to the relay armature 8 which is pivoted at 9 and held normally against the contact 10 by the spring 11. From the contact 10, the wire'12 leads to the transformer secondary at 13. From the back contact 14, the wire 15 leads back to and is connected with the wire 1-. The anode 16 is connected by wire 17 to the coil of the relay It, from which the wire 18 leads back to the transformer secondary through the current 'consumingdevice S, the ammeter A, the cut-out C and the dial switch 19. That part of the secondary be:

tween the points "5 and 13 is a lowvoltage section of the secondary winding, the potential drop therein being only sufiicient to heatthe bulb filament or cathode 6 at startmg.

Upon closing the charging line b coupling therein the current consuming evices S, the relay R is energized and the armature 8 breaks the contact at 10 and closes against thecontact at 14, so that thereafter there are two paths for the wave from the anode 16, one by way of filament 6, wire 7, armature 8, contact 14, wire 15 to wire 1-; the other from the opposite end of filament 6, direct to wire 4 so that the are between the cathode 6 and the anode 16 will distribute itself uniformly over the cathode heating filament 6, with no destructive efiect thereon because of overheating at any one point, because the effect of the loop 7, 8, 15 is to bring each end of filament 6 to the same potential, and thus equalize the drop from the center of the filament to either of its end terminals.

Upon opening the switch 19 or disconnecting the devices S, the relay it is at once tie-energized, the spring 11 breaks the contact at 1 1 and closes. contact at 10; but the currentnow supplies to cathode 6 is of low potential: that between the points 5 and 13, and hence it is not destructively heated.

The introduction of the cut-out G into the charging circuit is an additional safeguard against overloads. This cut-out is fully described in my prior Patent No. 1,231,200, dated June 26 1917, and need not be described here beyond setting forth the characteristic that when it is traversed by a current its cut-out contact remains closed for all normal potentials; but it may be so adjusted that an abnormal current can traverse its circuit only a predetermined period before automatically tripping,

It is to be understood that only one half of the A. C. wave from the transformer secondary is delivered to the device S, the other half not being used, when a single bulb is operated.

In Fig. 2, l have shown an arrangement for converting the entire A. C. wave into D. C. It embodies a substantial duplication of the outfit as thus tar described, with each bulb coupled into a low voltage section of the transformer secondary at each end thereof, with the charging circuit connected to the middle point of the secondary. The wiring in detail is as followsz- The wires 4: 4:" are tapped into the secondary at the points 5 5". and lead respectively to the cathodes 6" 6", from which the wires 7 7 lead to the armatures 8' 8"; contacts 10 10 are connectedrespectively to the points 13 13" of the secondary; wires 15' 15" connect the contactsl l 14; with the wires 4: 4"; the wires '18'18 are joined to form the common charging line which includes the D. C. current consuming device S. ammeter A, variable reactor V ll, time limit cut-out C and fuse F.

The dial switch 19 of Fig. 1 and the reactor V R of Fig. 2 serve the same purpose in the two forms of the outfit. The points of the dial switch are connected to the seve'ral taps on the secondary as shown so that the charging voltage may be controlled. The shifting of the reactor contact in the I charging circuit accomplishes the same purpose.

The ordinary current fluctuation is taken care of by the cut-out C; but any surging in the charging line might not be responded to quickly enough to avoid damage. and for this reason I prefer to place an additionirl safeguard in the form of a fuse F in the In some cases, I may introduce another monies This consists in the following instrumentalities, referring" to 5, the tripping arm of the cut-out C is provided with a horizontally-extending arm 22, immediately beneath which the small solenoid 20 is placed, so I through the ammeter A to the dial switch 19. The cut-out trip is connected directly into the transformer primary circuit by the wirest24c, 25. So that when the cut-out is tripped, the main A. C. line is opened, and further operation is stopped.

Inasmuch as many charging outfits are already on the market, each of which embodies the bulb B, transformer T and dial switch 19, it has been thought desirable to mount the relay lit, the cut-out C, and the tripping solenoid 20 upon a separate panel with binding screw connections thereon, ready to be installed into such a charging outfit as an individual unit. This form of unit is clearly illustrated in Fig. 6. The diagram of the wiring is clearly shown in Fig. 5, and needs no further description.

Tests of the arc rectifier as heretofore used show that the cathode filament 6 is very unevenly -heated, that a small white hot globule forms upon the point of connection between the filament 6 and the supporting wire, and that a small portion of the filament adjacent thereto is heated hite hot and begins to sag at that point, while the other end of the filament is much cooler. sometimes being barely red. Since this excessive heat rapidly deteriorates the filament. it follows thatany method of reducing it, or evenly distributing it over the length of the filament will lengthen its life. The' method and instrumentalities above described effectually accomplish this object, while the safety devices connected into the charging line effectually protect the outfitfrom damage due to short circuits or ovcrloads.

It is obvious that the same results may be accomplished by locating: a switch in the leads from the cathode 6 to the low voltage section of the secondary. In Fig. 7, I have shown a 4-way switch 28 with the cathode leads 29, 30 connected therewith. The anode lead 31 is connected through the D. C. load S ammeter A, and dial switch 32 with several points in the transformer secondary.

-As shown in the figure the switch is turned to connect the cathode 6 in series with the low voltage section of the secondary.- In

form of safety device into the charging liueFig. 8, the switch is shown as turned to til) passing A. C. therethrough to ionize the inert gas within'the bulb, and thereafter maintaming such ionizing effect by passing only the negative half of-the AIC. wave from the anode to the cathode, which is in effect, a pulsating D. C. wave, controlled by the D. C. consuming devices or load.

l i hile I have shown the several protective devices connected up in the load line from the anode, in the several figures of the drawing, it is obvious'that where the circumstances warrant it, any one or all of them may be omitted, or some'may be used and others omitted. Each case of installation will determine the necessary devices to be used. The gist of my improvement,-however, resides in the provision of means for initially connecting the cathode filament with the transformer section, and after thefilament sufliciently heats the gas within the bulb to 'ionize it so that the are may form between the filament and the anode, then to connect the cathode leads in parallel to the transformer secondary, so that thereafter those leads will carry only the negative half wave from the anode.

In practice, the are from the cathode to the anode seems. to play aboutthe middle point of the cathode, whereas in the prior way of using the bulb, the arc would play about one end of the filament where the intense heat would soon cause it to sag, and

ultimately to rupture immediately adjacent to the over-heated end.

I claim .1. In an arc rectifier system, the combina tion of a rectifier bulb having cathode leads connected respectivel} tQ the ends of a lowv voltage section of a transformer secondary with means for connecting said leads in parallel to a single point in said secondary, adapted to make the bulb completely selfexciting on load current.

2. In an arc rectifier system, the combination of a rectifier bulb having cathode leads connected respectively to a low voltage section of a transformer secondary, and its anode connected through D. C. consuming devices to another' oint in said secondary, and means .for ma ing said bulb continuously self-exciting on load current alone by connecting both of said cathode leads in parallel to one end of said low voltage section.

3. In an arc rectifier system, the combination of a rectifier bulb having a cathode normally connected in series with a low voltage section of a transformer secondary, with automatic means for connecting said leads in parallel to a single point in said second-- ary, adapted to shift the bulb excitation exclusivelyto either the low voltage section or to a load section of said secondary.

4. In an arc rectifier system, the combination of a rectifier bulb having a pair of cathode leads connected respectively to the ends of a low voltage section of a transformer secondary and an anode connected through a D. C. consuming device with another point in said secondary, and automatic means for connecting both 'of said cathode leads to a single point in said secondary, the cathode being wholly heated by the low voltage section when its leads are connected as first stated, and wholly heated by a load current section when connected to said single point.

5. In an arc rectifier system, the combination of a rectifier bulb having a pair of cathode leads connected to .the respective ends of a transformer secondary section, and an anode connected. through a D. C. consumiug device with another point in said secondary, and automatic means connected. into said anode for connecting said cathode leads in parallel to one end'of said secondary section.

' 6. In an arc rectifier system, the combination of a rectifier bulb, a transformer, and a D. C. consuming device, with leads from the bulb cathode respectively to the ends of a low voltage section of the transformer secondary, a lead from the bulb anode through said consuming device to another'point in said secondary, and means for connecting both of said cathode leads to a single point in the said low voltage section of thesecondary, adapted to cause current to flow in both cathode leads in. the same direction when these leads are connected as last recited.

7. In an arcrectifier system, the combination of a rectifier bulb, a transformer and a D. C. load, with cathode leads from said bulb to the respective ends of a low voltage section of the transformer secondary, an anode lead from saidbulb through sa d lead to said secondary, and automatic means cona D. C. consuming load, wire leads from the bulb cathode normally connected to the ends ofa low voltage section of the transformer secondary, a wire lead from the bulb anode through said load to another point in said secondary, and a relay in said anode lead for automatically connecting both of saidanode lead, and means actuated by said relay for connecting both of said cathode leads in parallel with a single point in said secondary.

10. In a rectifier system, the combination of a rectifier bulb, a transformer secondary, and a D. C. consuming load, cathode leads from said bulb to the ends of a low voltage section of said secondary, an anode lead from said bulb to another point in said secondary, a relay having connections with said cathode leads for connecting the same in parallel to a single point in said secondary, and a safety cut-out in said anode lead for opening said lead after a predetermined period of D. C. flow through said lead.

11. In a rectifier system, the combination of a bulb having an enclosed cathode filament and an anode, a transformer secondary, and a D. G. consuming load, leads from said filament normally connected in series with the ends of a low voltage section of said secondary, a lead from said anode connected through said load to another point in said secondary, a relay connected into said anode lead and having connections with said cathode leads for automatically closing the same in parallel to one end of said low voltage section, and means actuated by a current surge in said anode lead for actuating said relay to restore the normal connections of said cathode leads.

12. The method of protecting the cathode filament of an arc rectifier bulb which consists in first heating said filament by the passage of A. C. therethrough to ionize the inert gas contained within said bulb, and thereafter continuing said ionizing effect by the passage of the negative wave alone from the bulb anode to the cathode by connecting the cathode leads in parallel with the source of electrical supply.

13. In an arc rectifier, the combination of a rectifier bulb having cathode leads connected respectively to the ends of a portion of a transformer secondary, with means for connecting said leads in parallel to a single point in said secondary, adapted to change the cathode lead connections from a series connection with said portion to a parallelseries connection with said secondary.

, 14. In an arc rectifier system, the combi nation of a rectifier bulb, a transformer and a D. C. consuming load, wire leads from the bulb cathode normally connected to the ends of a low voltage section of the transformer secondary, a wire lead from the bulb anode through said lead to another point in said secondary, and a relay controlled by the load current for automatically connecting both of said cathode leads in parallel with a single point in said secondary.

15.11! a vacuum tube system, a source of A. C. supply, a filamentary cathode tube connected thereto and means for first separately exciting said tube, by a current in series with the filament and subsequently by load current traversing the filament leads in parallel.

16. In a rectifier system, the combination of a rectifier tube having a filament cathode,- an inductive winding having a loadsection and an excitation section connected together, and means for initially connecting the filament leads across the excitation section and sublsequently connecting them to one of its on s.

17. The method of operating a vacuum tube, having an anode and a filamentary cathode, which consists in passing excitation current through the filament leads and subsequently passing space current from the anode through said leads in parallel.

18. The method of rendering a hot Wire cathode tube'self-exciting on load current which consists in exciting the tube by one ormore sources of electro-motive force in the wire filament circuit. and simultaneously closing that circuit upon itself while'removing said sources of electro-motive force therefrom.

EARL H. ROLLINSGN. 

